The invention pertains to a process and a device for the treatment and in particular the cleaning of fluids, especially flue gases and so forth, whereby the process is preferably executed according to the countercurrent method with the aid of a pourable solid that is present in form of a bulk material. At least one bulk material travels from the top towards the bottom through at least one reaction chamber, and at least one fluid flows from the bottom towards the top through the bulk material layer within the reaction chamber. The process is preferably executed with the aid of a flow-past base in order to distribute the fluid over the cross section of the reaction chamber and to let the bulk material penetrate towards the bottom. In a known process for the cleaning of flue gases, the flue gas is usually conveyed through two, preferably even three, cleaning stages, whereby an adsorptive and/or catalytically effective bulk material is used in the last two cleaning stages.
For the cleaning of flue gases it is known to remove impurities such as HCl and/or SO.sub.x and/or heavy metals such as Hg as completely as possible from the flue gas with the aid of a first bulk material, in particular hearth furnace coke, after a so-called wet cleaning process is executed. Nitrogen oxide (NO.sub.x) is removed from the previously cleaned flue gas in a subsequent cleaning stage by activated coke or activated charcoal consisting of glance coal. This process is executed by introduction of ammonia (NH.sub.3) as reactant. H.sub.2 O and N.sub.2 are formed during this reaction. This two-stage cleaning process with only one bulk material is very demanding but is generally considered necessary because of the complex reactions of the components involved.
While the exhausted hearth furnace coke must be regularly removed, regenerated, incinerated or disposed, the last cleaning stage (denitration) can usually be operated like a fixed bed. Although this stage pertains to a catalytic reaction, it was established that an occasional exchange of the bulk material is necessary.
Next to the numerous reaction possibilities of the components involved, the presence of fine-particle impurities such as dust and so forth creates substantial problems during the operation of known bulk material reactors.
The problem of zones with reduced bulk material exchange in the reaction chamber exists in this known flue gas cleaning process. This problem primarily occurs in fluidized bed reactors through which the fluid flows in a transverse manner and in which louver-like fluid intake and fluid outlet walls are provided. The zones of poor bulk material exchange lie in the area of the louvers. Conglutinations, cakings and similar agglomerations of the bulk materials can occur in the zones of poor bulk material exchange inside the reaction chamber, which means that these agglomerations consistently increase the pressure loss in the bulk material layer over time. However, the problem of zones with poor bulk material exchange inside the reaction chamber can generally be controlled. A fluidized bed reactor with a special flow-past base that operates according to the countercurrent method (World Patent 8808746) was suggested for this purpose.
Even if the problem of zones with poor bulk material exchange within the reaction chamber is solved--whether it be by means of reaction chambers through which the liquid flows in a transverse manner or reaction chambers that are operated according to the countercurrent method--a further problem presents substantial difficulties during the operation of the bulk material reactor: a "swelling" of the bulk material particles can occur under certain conditions. The simultaneous presence of nitrogen oxides, ammonia and "acidic" inorganic compounds such as SO.sub.2, SO.sub.3, HCl, HF or similar compounds can under certain conditions lead to a "swelling" of the bulk material particles consisting of coal or coke (popcorn formation). The bulk material can reach twice its thickness, which means eight times its volume. This reaction is primarily observed in the zones where the liquid enters into the bulk material layer. This "popcorn" not only stresses the reactor but also leads to problems during the removal of the swollen bulk material particles since this "popcorn" is mechanically very unstable and thus easily crumbles during removal.